JPH0241697B2 - - Google Patents

Abstract

A method and apparatus for optically making physical measurements of materials which deform upon application of heat thereto. The device comprises a source of light, an at least partly transparent chamber having a heating source which can be programmed to operate as a function of time, and with a porous support designed to support a deformable material within the chamber. A photo-electric receiver 5 and an optical lens 7 are also provided for imaging of the material during deformation on the photo-electric receiver. In order to perform the imaging, the source of light, the porous support, the photo-electric receiver and the optical lens 7 are optically aligned. In a specific application, the apparatus can be used to determine the wetting power of pitches.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device for measuring the deformation of materials due to heat, and in particular to a device for measuring the wetting force of molten materials (pitch).

(Problems to be solved by the prior art and the invention) It is well known how to measure the temperature at which a substance changes from a solid state to a viscous state to a liquid state under the action of heat. It is being Ball softening temperatures and ring softening temperatures, or Dijlan melting points or Kremer-Thurnau (KS) softening temperatures, have therefore been defined for thermoplastic materials. However, these methods do not provide any information about the reaction of the material while it is being heated.

It is useful to know the nature of the shape change of a material subjected to the action of heat, in particular its evolution relative to the support to which said material is bound, and also to which it is itself resistant to the action of heat. Not affected. In the specific field of pitch binders for electrodes, it is useful to know the wetting power of the pitch, making it possible to estimate values for electrode manufacture. In particular, it is important to know the temperature at which a given pitch is completely adsorbed onto a given coke, and also to know how this adsorption effect occurs, in particular how the molten pitch is absorbed into the pores of the coke. It is useful to know how to penetrate the quality part.

The object of the invention is to provide a device for measuring the wetting power of molten substances (pitch).

(Means for Solving the Problems) In the present invention, in a device for measuring the wetting force of a molten substance, which includes a light source, a light receiving device, and a heating device, the measuring device is disposed between the light source and the light receiving device. and having a chamber that is partially transparent to allow light from the light source to pass to the receiver, the chamber having a porous support thereon for receiving the substance to be measured and a heating device therein. It is configured.

(Example) As shown in FIG. 1, the following is a general description:
The measuring device of the invention comprises a light source 1, a heating device 3 whose operation can be scheduled as a function of time, and a porous support 4 designed to receive a substance 6, at least partially transparent. a light source 1, a porous support 4, a photovoltaic luminometer 5, and an optical lens 7 capable of forming an image of a substance 6 on the photovoltaic luminometer 5. , and the optical lens 7 are optically aligned.

A diaphragm or an optical lens may be inserted between the light source 1 and the chamber 2 to generate a parallel beam of light from the light source 1.

Conveniently, the porous support 4 can rest on a base, which may rest on the bottom of the chamber 2 or be suspended from the top opening of the chamber 2.

Substance 6 is a rigid body at room temperature. Advantageously, the material has a regular shape, preferably cylindrical or parallelepiped.

The properties of the light source 1 depend on the properties of the photoelectric luminometer 5. If the photoelectric luminometer consists of a photomultiplier tube and is provided with a vertical gap that forms the image of the material 6 formed by the lens 7, then
The light source must have a certain intensity and emit light at a wavelength that satisfies the characteristics of the photomultiplier tube. In such cases it would be possible to use conventional light sources, ie filament lamps supplied with a stable voltage, or laser light sources. If the photoelectric luminometer consists of a vertical bar of microphotodiodes, the light source need not have a constant intensity or be monochromatic; the microphotodiodes, as will become clear, It operates on the "all or nothing" principle. However, in such cases it is necessary that the intensity of the light emitted by the light source is sufficient to saturate the microphotodiode.

The chamber 2 must be at least partially transparent in order to pass the light beam originating from the light source 1. It may also be completely transparent, for example made of a glass cylinder, the axis of which is perpendicular to the light beam and perpendicular to the plane formed by the support of the device. be. The chamber may also be partially transparent and consist of a vessel, for example in the form of a parallelepiped, in which case the two walls parallel to the beam are opaque and the two walls perpendicular to the beam are opaque. The wall is transparent. Advantageously, the transparent walls of the chambers facing each other are made of a material that is not deformed by heat. This material is made of glass, for example Pyrex grade glass.

The light source 1 may be located inside or outside the chamber 2. If the light source is located inside the chamber, the chamber need only have one window for passing the light beam.

In a more detailed description of the embodiment of the invention shown in FIG. 1, a light source 1, a porous support 4,
The photoelectric illumination meter 5 and the optical lens 7 (light receiving device) are geometrically aligned. In other embodiments, these elements are not geometrically aligned. However, the device also has a reflective element located in the path of the light beam originating from the light source 1, either in front or at the rear, the light of which is interrupted by the substance 6. This reflective element may be, for example, a mirror or a total internal reflection prism located inside the chamber.

The porous support 4 has a porosity (ratio of pore volume to total volume) of 0.1 to 0.9 and may consist, for example, of a powder bed or pellets of sintered material contained in a boat. The powder contained in the boat is
For example, it has a particle size distribution of 10 to 1000 microns. The pellets of sintered material have, for example, a pore diameter of 10 to 200 microns.

The device according to the invention operates as follows. Substance 6 is placed on porous support 4 and chamber 2
is lower than the temperature at which the substance 6 begins to deform. The light source 1 is turned on and arranged, and the optical lens 7 is adjusted so that an image of the substance 6 is formed on the photoelectric luminance meter 5. It is confirmed that at least a portion of the porous support 4 partially blocks the light beam. If the photoelectric illumination meter 5 is made of a bar of microphotodiodes, the device is fine-tuned using a counter that indicates the number of diodes that are not illuminated. Chamber 2 is heated according to the known law T=f(t), where T
is temperature and t is time. At a certain temperature the material 6 begins to deform and the amount of light received by the photoelectric luminometer 5 increases proportionally as the height of the material 6 placed on the porous support 4 decreases. Therefore, the photoelectric illumination meter 5 generates a voltage proportional to the decrease in height (h). This voltage can be traced with a recorder to the curve h=f(t) with respect to the known heating law, or if the recorder is coupled to the temperature program of the chamber, the curve h=f(t). f(T).

The sophistication of the device makes it possible to trace the contour of the material 6 during the deformation process at any point in time. For this purpose, the photoelectric luminometer 5 is mounted in such a way that it can be moved transversely to the beam of light, so that at any time it is possible to scan the imaged area of the substance 6. can. This movement must be fast enough to allow almost instantaneous sliding over the contour of the material 6 that is being deformed at a given temperature. Once this is possible, interesting information is obtained relating to the angle formed between the base of the substance 6 and the porous support 4, indicating whether they have become mutually wettable or non-wetting. It is a measure of wettability. The XY recorder for contouring the material and the h=f(t) or h=f(T) recorder for measuring the maximum height of the material 6 can be used simultaneously.

The device according to the invention makes it possible to carry out reliable and reproducible measurements without the need for permanent control by the operator.

The invention is applicable to all materials that deform under the influence of heat, such as novolac resins, pitches, and substantially opaque thermoplastic materials.

The porous support 4 is preferably, for example, a layer of coke powder contained in a boat or pellets of sintered glass. According to the procedure described above, the measurement is interrupted when the pitch sample is completely adsorbed onto the porous support 4.

The following examples are intended to illustrate the invention.

Examples 1 and 2 The porous support 4 used was a layer of coke powder, the particle size distribution of which was between 40 and 400 microns, of which 88% was between 80 and 125 microns;
The material 6 used was also two pitcher pellets with almost identical physical and chemical properties. However, these reacted differently in the manufacture of electrodes. Sample 1 reacted poorly and sample 2 was in contrast. Using the device according to the invention, a curve such as that shown in FIG. 2 is obtained, showing the pitch pellet height as a function of temperature. The curve representing pitch sample 2 shows that certain constituents therein are very difficult to adsorb by the layer of coke powder.

Example 3 The porous support 4 used was a sintered glass pellet with a pore diameter of 90 to 150 microns, and the material 6 used was a novolac-based phenol formaldehyde resin, which was composed of phenol and formaldehyde. obtained by condensing in an acidic medium. This resin has a Duran softening point of 85 degrees Celsius. FIG. 3 shows the curve h=f(T) obtained using the device according to the invention. The first flat end corresponds to the transfer of the resin pellet into a droplet. The temperature at the center of this flat end is the softening point. The subsequent curved portion shows how the sample is adsorbed onto the porous support 4.

(Effects of the Invention) In the present invention, it is possible to accurately and easily measure the wetting power of a molten substance by taking into account changes in the height of the substance due to heat.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the measuring device of the present invention, and FIGS. 2 and 3 are curves representing the relationship between the height and temperature of a substance. In the figure, 1... light source, 2... chamber,
3... Heating device, 4... Porous support, 5... Photoelectric luminometer, 6... Measuring substance, 7... Optical lens.

Claims (1)

[Claims] 1. A molten substance wetting force measuring device comprising a light source 1, light receiving devices 5 and 7, and a heating device 3,
The measuring device comprises a chamber 2 disposed between the light source and the light receiving device and partially transparent so that light from the light source passes to the light receiving device, the chamber containing the substance 6 to be measured. A wetting force measuring device characterized in that it comprises a porous support 4 received thereon and the heating device 3 therein.